Telegraph storage system



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TELEGRAPH STORAGE SYSTEM' Filed June 28,J 1946 1.a sheets-sheet 1a /NVEA/ron G. A. LOC/(E A TTOR/VE V Patented Oct. 25', 1,949

UNITED STATES TENT OFFICE TELEGRAPH STORAGE SYSTEM rated, New York, York Application June 28,

3 Claims.

This invention relates to telegraph switching systems in which messages are stored in switching oices, and more particularly, to improvements in such systems for the purpose of preventing or reducing temporary overloading of outgoing lines or channels of transmission with certain classes of messages with resultant exclusion from those lines of other messages or classes of messages.

Arrangements according to the invent-ion or involving the principles thereof may be embodied in different forms of system. In order to elucidate the principles of the invention and make manifest arrangements comprising exemplary embodiments thereof, it will iirst be necessary to summarize the principal features of a type of existing system in which exemplary types of the invention may be incorporated.

In an existing type of system a message storing and automatically operating message directing switching office is provided which may be conn nected by trunk lines to other identical or similar offices. To the central switching oiiice there are connected a number of lines or channels oi transmission which are usually duplexed, that is, they may transmit in both directions simultaneously and may utilize the same wires for incoming and outgoing transmission or transmission over intermediate sections between oiices in accordance with well-known telegraph duplex practice, or they may use separate and oppositely directed paths of transmission, two of which, incoming and outgoing, are associated together as a duplex two-way line. The invention does not exclude nali-duplex lines or channels which are or may be used as a part of the lines or channels of such a system or as the entirety thereof. At one or more outlying stations of such a channel of transmission, which will often hereinafterior convenience be referred to as a line, there are provided telegraph transmitters usually of the automatic type, or which may be manually operated, with associated teletypewriter or code receivers. The transmitters and receivers may be used together as a station or some stations may have transmitters only and others receivers only or some stations may have two different receivers, one of which may be provided with multiple code forms, and the other provided with means for producing a single copy only of the received message. Means are provided at the central switching oiiice whereby the outlying transmitters are assigned times or opportunities to transmit to the central oiflce where at the incoming transmitted messages are recorded in a reperforator. There may also be single station lines connected to trans- N. Y., a corporation of New 1946, Serial No. 679,956

mit into a similar reperforator in the central oiice and there may also be originating stations inthe central oflioe consisting of a keyboard perforator into which message material may be recorded for transmission to one or more of the various outlying offices of the system. Incoming messages recorded by the central olice reperforato'rs or recorded by the keyboard perforators of the originating stations at the central oice are self-directing. Usually each message begins with one or more Letters shift code combinations, then an upper case or Figures shift combination, followed by a combination which, in general, may be used as an end-oi-message message signal to clear out any false or erroneous connections acci-I dentally established through the system (if there be such), then one or more letters characters, then two code combinations comprising the address, followed by the message proper, followed by an upper case code combination used as an` endof-message message signal. The two code combinations which comprise the address function coadjuvantly to select a path of transmission across the switching oiiice from an automatic transmitter controlled by the stored message along with its address to a reperforator associated with an outgoing line or channel of transmission which, in general, may be any one of the duplex lines or half-duplex lines referred to previously. Each outgoing line in the exemplary type of sys tem is provided with two reperforator-transmitter sets (there may be more) which are so ranged as to transmit their messages alternately one after the other, first a message from one transmitter then a message from the other transmitter so long as both are provided with messages to bertransmit'ted. When only one is provided with such messages it proceeds to transmit messages one after the other until its message material is exhausted or the other transmitter is provided with message material comprising one or more messages. Reperforators receive messages from the incoming lined transmitters over one or another of two types of paths. Paths of both of these types are selected by each two code combinations constituting an address but the reperforators are connected to one or the other only and the other remains idle. If the path connected is such as to lead to a reperiorator associated with line connected to one or more outlying stations, the iirst code combination, after it is used to select the path, is not transmitted over'the used path but is absorbed or dropped. The second code combination is transmitted over the path and appears in the outgoing line reperforator and is transmitted over the outgoing line by the outgoing line transmitter to control a switching selector remotely located on the line and it causes the selective conditioning of the receiver constituting the proper address to receive the message. If the two code combinations which select a path across the office are such as to select a reperforator associated with a trunk circuit leading to another switching office, the transmission across the omce occurs over another type of path over which both the code combinations of address are transmitted to be recorded by the reperforator associated with the trunk line. In this prior type of system there are also arrangements sometimes referred to as intercept circuits. One kind of intercept circuit is known as a wilful intercept circuit. In accordance with the operation of this arrangement, upon the operation of a certain key or keys, messages intended for certain stations or certain outgoing lines, instead of being directed to an outgoing line reperforator, are directed to a wilful intercept reperforator and stored for subsequent retransmission if and when the keys are restored and other appropriate keys properly positioned. The transmitter associated with the wilful intercept reperforator is coordinate in function to the transmitter associated with the perforator of a message originating station or position in the central switching oice. Messages transmitted to the wilful intercept reperforator proceed thereto over a path which sends to the reperforator both the directing code combinations. A system of the type thus described is known and. is described in a copending patent application of the joint inventors D. E. Branson- F. S. Kinkead-J. A. Krecek-G. A. Locke, Serial No. 448,878, filed June 27, 1942, and which issued as Patent 2,430,447 on November 11, 1947.

In the operation of a system such as just described, the system or certain lines of the system may lbe fully occupied during certain hours of the day with regular business messages whose expeditious transmission is desired. There may be certain other times when the system is lightly loaded with such messages and it is desired to make use of it for relatively long messages for which expeditious transmission is not particularly necessary. With respect to such long messages originating at the switching ofce attendants may introduce them into the system during period of light loads but this requires special attention on the part of operating personnel. Moreover, let it be supposed that the control board shows a particular outgoing line 'to be lightly loaded and the operating personnel at such times initiates the transmission of two or more long messages directed to a particular outgoing line. These long messages each may seize a path directed to outgoing line reperforators and if there are two such reperfcrators, both might become occupied by two long messages. To make the situation concrete, if each of these messages require six minutes transmission time (herein assumed maximum transmission time of a long message) and one seizes each of the two reperforators associated with an outgoing line, the line will be occupied for twelve minutes because each of the two transmitters associated therewith as stated above operate alternately to send one message each when both are supplied F with messages. Let it be supposed that at the instant of initiating transmission of such long messages from an originating station at the switching oiiice a particular outgoing line vis idle but immediately thereafter several short messages arrive from outlying stations directed to the same outgoing line, then it would be almost twelve minutes before the outgoing line is free and available for the transmission of these short messages, several of which may become accumulated in the meantime. Furthermore, in the case of long messages originating at outlying stations the attendants thereat ordinarily lack present knowledge of conditions at the central switching cnice and may initiate the transmission of long messages at a time when the particular outgoing line to which they are directed is or is about to be fully occupied. Such long messages arrive at the central oflice and immediately in their vproper turn preempt the outgoing line reperforators to which they are directed for periods of time up to six minutes or mutiples thereof which may result in an undesired delay of short regular business messages. It therefore becomes desirable to prevent the clogging of the storage tape of outgoing line reperforators of the system with too many long messages and an object of this invention is to provide methods of operation and equipment whereby this prevention is automatically accomplished. In the exemplary embodiment each outgoing line is provided with two transmitters as stated above and these transmitters when fully loaded operate in alternation to send messages stored by their associated reperforators to the outgoing line.

The object of the invention is accomplished by intercepting long messages which originate .at outlying stations in a special intercept circuit or circuits and so condition their delivery from such intercept circuits as well as the delivery of long messages originated at the central switching ofce to outgoing line reperforators that delivery of any long message to outgoing lines reperforator-transmitter sets is restricted to one only of the two reperforator-transmitter sets associated with a given line and further restricted in that after delivery of one long message to this reperforeter-transmitter set no further long message may be delivered thereto until a previous long message is completely transmitted and further restricted in that the other .associated reperiorator-transmitter set of the line has at some time or other been Void of message material after the preceding long message has been delivered to the one available reperforatortransmitter set which is open to receive .such messages, and further restricted in that the reperforator-transmitter set which is assigned .to receive and transmit long messages must be void of message material before it is permitted to receive any long message. In accordance with this arrangement an outgoing line can not usually be utiliaedvfor more than six minutes while ordinary Amessages are awaiting transmission in the switching ofce over that line although a long message may proceed to its destination before one or more short messages. Thus, for example, let us designate one reperforator-transmitter set on a line as No. 1 and the other which is assigned to receive long messages as No. 2. It may happen that after being idle for some time the reperforator-transmitter of set No. l will receive several messages in succession for transmission and at the same time the reperforatortransmitter set No. 2 which has become idle will receive and accept a long message. As soon as the first message has been cleared out `of reperforator-transmitter set No. 1 the reperforatortransmitter set No. 2 will seize and preempt the line for transmission of its long .message where- 

